Counter-measure dispensers are known today. The compartments of the dispenser are used for storing and launching counter-measures from a vehicle, such as an aircraft.
A counter-measure dispenser is known from WO 00/59782 disclosing a well functioning arrangement for preventing the occurrence of vibration disturbances, which are primarily caused by inherent oscillations in the empty compartments. During use of the dispenser counter-measures are being launched from the compartments for diverting an enemy attack, e.g. in the form of a target seeking missile. The solution in WO 00/59782 is to arrange a spoiler in front of the opening of the compartment for creating a low dynamic pressure across the opening thereby reducing the interfering noise and vibrations.
U.S. Pat. No. 3,430,533 discloses an arrangement for sealing the counter-means compartments after launching counter-measures. Each compartment has a piston arrangement for sealing the opening, thereby eliminating the aerodynamic loads and vibration effects which are present whenever an open compartment otherwise is subjected to supersonic velocity air streams. The sealing is achieved by the individual piston in each compartment which, after launching of the respective counter-measure, will form an aerodynamically smooth surface with the skin of the dispenser unit.
It is desirable to eliminate the interfering noise and vibrations created by the opening of the compartment after the launch of the counter-measure from the dispenser. The noise is undesirable since it can be used for localisation of the vehicle and the vibrations may cause damage to the vehicle or dispenser structure. At the same time it is desirable to achieve an uncomplicated dispenser unit with as few movable parts as possible and which will have reliability in operation.